Let's make a bit of clarity on terminology, first. If you search "soul sleep" in Wikipedia, you get redirected to Christian mortalism.
Whatever term one adopts (soul sleep, Christian mortalism) or even fancy ones (psychopannychism, thnetopsychism), the concept is quite simple: when one is dead, one is truly dead (certainly unconscious, BTW) and only God can bring back to life one's whole person.
What about the "soul"? The Bible says nothing serious about the soul apart from the body. Of course the standard questions, at this point, are: What about The Witch of Endor (1 Sam 28:1-25)? What about The Rich Man and Lazarus (Luke 16:19-31)?
As to the former, we are talking about a witch. What she "saw" (and Saul never saw) could easily be a conjuring trick and/or a satanic manifestation.
As to the latter (admitting that the parable is authentic words of Jesus, which there is no way you can say from the text) it could be, on the part of Jesus, a concession to folk tales on the "beyond" (more or less similar to the concessions that the Church has made in the course of time). What matters is the final reply that "Abraham" gives to the "Rich "Man":
‘If they do not hear Moses and the prophets, neither will they be
persuaded though one rise from the dead.’ (Luke 16:31)
Now we can confront the OP Question. I don't much care for the JW's (I consider them today's heirs of Arianism), but I have looked at the article linked by @Kris, and I find nothing wrong with it, neither logically, nor theologically, nor scripturally. In particular, this statement cannot be objected to:
If there were no resurrection, then Abraham, Isaac, and Jacob would
remain forever in the clutches of death.